Design theory and conceptual design: contrasting functional decomposition and morphology with parameter analysis

Over the last several decades, functional decomposition and morphology has become the most common conceptual design method to appear in design textbooks. Although criticism toward systematic design in general and functional decomposition and morphology in particular has increased, most design educators keep teaching this method. Some of its weaknesses are demonstrated in this paper on a textbook example, followed by proposing parameter analysis as an alternative or complementing methodology. Parameter analysis was initially developed as a descriptive model of reasoning in design and later turned into a prescriptive model for doing innovative conceptual design. This methodology centers on repeatedly identifying dominant conceptual-level issues and relationships ("parameters"), implementing these concepts as configurations, and continuously evaluating the evolving design. The usefulness and power of parameter analysis are shown through several case studies, its relation to modern design theories, and its applicability to training designers. The tight connection between the teaching and practice of engineering design suggests that adopting a new educational methodology will bear fruits in industry a short time thereafter.